Sunday, March 11, 2007

The Magic of Hollywood

GreenScreen, 20070311We had decent weather this weekend, and in spring a dog owner's thoughts turn to making films. I broke out the equipment and set to work.

My special effects equipment consists mainly of an inexpensive Canon digital video camera and a painted bulletin board as a "green screen". The Christmas video uses animation made on the computer, but most live action special effects in Pappy movies involve the simple layering of still and moving images where I have made the backgrounds transparent. Making a film sequence have a transparent background is done by filming against a background of some uniform color that isn't in your subject-- most commonly pure blue or green, but it could be any color. Then you use your computer and a video editing program like Adobe Premiere Elements to process this video to remove the background color. The area you want to render transparent is called the "key". Thus, the process of using a specific color to create your transparency key is called Chroma Keying.

Your digital photos can be opened in Adobe Photoshop Elements or a similar photo editing program to select and delete portions of the image, leaving these areas "transparent". Since you can manually draw a mask around the subject in a still photo, you don't have to use a green screen. Saving these to PNG format allows you to retain this transparency information (called the "alpha channel") so that you can use that image in front of your video-- this is called a matte shot.

Finally, you superimpose all these images and videos together against a solid background in your video editing program. It's very much like creating a moving collage. Now, don't all of you go racing out to make your green screen movies. Somebody has to sit back and watch them.

5 comments:

Gus said...

Me, Me, I'm volunteering to just watch. There is no hope for muzzer, she got lost right after the green screen bit! Sheesh.

macgoogle said...

Ah yes, the good old green screen. Haven't played around with DV since my DVC broke. Must get it serviced when we have the money to fix it.

Texas's Dad.

Charlie Kelley-Church said...

Little to much TMI there for me! but glad you had a nice day.

C-K-C

Charlie said...

Have been wondering how to do that! Thanks for the tips!!
- Charlie's mom

Pappy's Fella said...

Gus,
We need our viewers as much as our directors.

Magoogle,
It's a fantastic time waster. I probably spend five or six hours per minute of video.

CKC,
It's definitely not for everyone, but on a lot of levels the concept is startlingly simple. It's the techniques that are baffling. I find it interesting because it explains so many effects used on TV and movies.

Charlie,
Sure. It's a surprisingly low budget special effects technique since the advent of digital photography.